Rotating shuttle drive mechanisms

ABSTRACT

A drive mechanism for a rotary shuttle in which the shuttle is operatively connected to a rotary actuator by means of a pinion extending therebetween and serving as a radial driving key. In order to pass needle thread loops between the shuttle and the pinion, the pinion is turned slowly about its own axis during rotation of the shuttle so that the thread loops will be carried in one of the radial indentations between adjacent pinion teeth.

United States Patent Ketterer 1 ROTATING SHUTTLE DRIVE MECHANISMS [72] Inventor: Stanley J. Ketterer, Jamesburg, NJ.

[73] Assignee: The Singer Company, New York,

[22] Filed: June 7, 1971 [21] Appl. No.: 150,608

[52] U.S.Cl., ..l12/l89 [51] Int. Cl. ..D05b 57/08 [58] Field of Search ..l12/189, 190,191,193, 185, 112/181, 184

[56] References Cited UNITED STATES PATENTS McKenzie ..1 12/189 1451 Oct. 17, 1972 2,851,978 9/1958 Eriksson 12/189 X Primary Examiner-H. Hampton Hunter Attorney-Marshall J. Breen, Chester A. Williams, Jr. and Robert E. Smith [57] ABSTRACT A drive mechanism for a rotary shuttle in which the shuttle is operatively connected to a rotary actuator by means of a pinion extending therebetween and serving as a radial driving key. In order to pass needle thread loops between the shuttle and the pinion, the pinion is turned slowly about its own axis during rotation of the shuttle so that the thread loops will be carried in one of the radial indentations between adjacent pinion teeth.

4 Claims, 8 Drawing Figures PATENTED OCT 1'! i972 SHEET .1 UF 2 I N VEN TOR Stanley J. Kefierer Kim/2 GEM/Z ATTORNEY INVENTOR.

' 86 Stanley J. Ketterer 73 70 BY :WITNESSI 7 84 J; MZ

ah Mi LMJ/ ATTORNEY BACKGROUND OF THE INVENTION A shuttleas is well known in the sewing machine art, is a lockstitch forming loop taker which accommodates a supply of locking thread, usually on a bobbin stored in the shuttle and forms lockstitches by passing bodily through each successive needle thread loop, thereby concatenating the needle and locking thread into lockstitches. In the process of stitch formation using a shuttle, therefore, each loop of needle thread must pass between the shuttle and the mechanism of the machine for imparting movement to the shuttle. Where the shuttle is oscillated back and forth during each stitch forming cycle, the reversal of direction of the shuttle drive elements naturally provides clearance for the needle thread loops to pass therebetween. Where the shuttle is to be rotated continuously in one direction, however, a gap or clearance for passage of the thread will not ordinarily be formed during the shuttle operation. Where sewing speeds are low it is possible to rely upon the tension in the needle thread to pull the needle thread loops between the driver of the shuttle, but as in industrial sewing machines, where the sewing speeds become appreciable, the driving forces necessary to rotate the shuttle become sufficiently large that the sewing threads cannot simply be pulled therebetween without serious risk of thread breakage and adverse influence on the stitch process.

Prior known rotary shuttle drive mechanisms in which provision has been made to provide an opening through which needle thread loops might be passed between the shuttle and the shuttle driver have involved elements required to be imparted harsh motions or to be driven at highspeeds equal to or many times greater than the speed of operation of the shuttle. Such prior rotary shuttle drive mechanisms have tended to be noisy and have tended to wear abnormally high rates.

SUMMARY OF THE INVENTION It is an object of this invention to provide a drive mechanism for a rotary shuttle in which a connection element arranged between the shuttle and the shuttle driver moves bodily at the same speed as the shuttle driver and in addition, is driven at a fraction of the speed of the shuttle in order to move a thread accommodatin g indentation relatively to the shuttle at a speed just sufficient to pass needle thread loops therebetween during the stitch formation operation. The above object is attained by the provision of a keying element between the shuttle driver and the shuttle which takes the form of a pinion of which the teeth mesh with a stationary screw formed in the shuttle housing of the sewing machine. The pitch of the pinion teeth and of the stationary screw with which they mesh is chosen to provide for rotation of the pinion about its own axis at a fraction of the speed of rotation of the shuttle so that a radial indentation in the pinion between the teeth thereof may accommodate and shift each needle thread loop which is seized by the shuttle through the shuttle driving connections.

2 DESCRIPTION OF THE DRAWINGS With the above and other objectsand advantages in view of this invention will be described hereinbelow, with reference to the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents an end elevational view of a sewing machine having a shuttle driving mechanism of my invention applied thereto,

FIG. 2 is an enlarged vertical cross-sectional view taken substantially along line 2-2 of FIG. 1 through the longitudinal axis of shuttle rotation,

FIG. 3 is an exploded perspective view of the shuttle housing, the shuttle and the shuttle driving mechanism of this invention,

FIGS. 4,5, 6 and-7represent elevational views of the face of the shuttle each taken at a different position of rotation of the shuttle during a typical stitch forming cycle and including a representation of the needle thread loop being manipulated by the shuttle, and

FIG. 8 is a cross-sectional view taken substantially along line 8-8 of FIG. 6 illustrating the needle thread loop as it is passing between the shuttle. and the shuttle driving mechanism.

Referring to the drawings, this invention is illustrated as embodied in a conventionally organized sewing machine including a frame having a work supporting bed 11 from which rises a standard 12 carrying a bracketarm 13 overhanging the bed. A thread carrying needle 14 is secured to a needle bar 15 supported in the bracket arm and driven by a mechanism (not shown) in timed relation with a rotary bed shaft 16 illustrated in FIGS. 2 and 3. The bed shaft is preferably imparted one revolution for each cycle of reciprocation of the needle. As illustrated in FIG. 1 a needle thread take-up member 17 and a needle thread tension device 18 are carried by the bracket arm and serve in a conventional manner to influence the needle thread which extends to the thread carrying needle 14. The needle 14 reciprocates endwise through aneedle aperture 20 in a throat plate 21 on the work supporting bed 11 of the sewing machine and cooperates beneath the throat plate with a shuttle indicated generally at 22. Also arranged beneath the throat plate is a work feed'dog 23 which may be carried by a feed bar 24 which is imparted rising and falling movements by a feed lift rock shaft 25 by way of a rock arm 26 and a link 27, and to which feed advance and return movements are imparted by a rock frame 28 fast on a feed rock advance. The feed dog 23 works through slots 30 in the throat plate in opposition to a presser device 31 supported on a presser bar 32 carried in the bracket arm 13.

Referring to FIGS. 2 and 3,. the shuttle 22 is preferably fonned with a circular bearing rib 40 which extends from a flat rear face 41. The shuttle is formed with a body portion 42 provided in the front face with a bobbin accommodating cavity 43. As shown in FIG. 8, a central stud 44 may be formed from the flat rear face 41 into the bobbin accommodating cavity 43. A flanged bobbin seat 45 is retained on the stud 44 by a screw 46 which can adjust the pressure between the flanged bobbin seat and a friction washer 47 which is arranged against the flat rear face 41 of the bobbin. The flanged bobbin seat is thus rotatable on the seat 44, subject to frictional resistance to turning which may be regulated by the screw 46. An annular friction ring 48 set into the flanged bobbin seat 45 constrains a bobbin 49 on the bobbin seat 45. Thread which is wound on the bobbin will therefore, have a tension applied thereto as the thread is withdrawn. It will be understood that the above described means for accommodating a bobbin in the shuttle and for applying a tension to a locking thread wound on the bobbin does not form adirect part of this invention and any other suitable bobbin housing and bobbin thread tensioning means may be used with the present invention.

The bearing rib 40 of the thread is formed with a gap 59 defining at one side a needle loop seizing beak 60 adapted as shown in FIG. 4 to seize and to distend loops of needle thread N during operation of the sewing machine. At the opposite side of the gap 59, the shuttle bearing rib is formed with a needle thread loop detaining finger 61 which serves as shown in FIG. 7 to engage each needle thread loop N after it has been passed completely about the shuttle to prevent the loop of thread from flying out of control as it is drawn into the work being stitched.

Referring to FIGS. 2 and 3, a shuttle housing block 70 is fixed in the sewing machine bed and formed with a bearing surface 71 for the bed shaft 16. The bearing surface 71 opens upon a cavity 72 which is provided at the mouth thereof with a raceway 73 in which the shuttle bearing rib 40 is journaled for rotation. A semi-circular shuttle retainer 74 and a resilient fastening clip 75 are secured by a fastening screw 76 on the exposed face 77 of the shuttle housing block 70 to constrain the shuttle 22 in the raceway 73.

As shown in FIG. 2, the bed shaft 16 protrudes into the cavity 72 in the shuttle housing block and in the cavity 72 a shuttle driving block 78 is secured to the bed shaft 16 by a set screw 79 and by a drift pin 79'. The shuttle driving block is formed with a radial slot 80 in which a pinion 81 is constrained. The pinion is journaled in the shuttle driving block on an axle pin 82 secured therein, so that while it may turn on its own axis in the shuttle driving block, the pinion will be snugly supported against tilting by the closely fitting radial slot 80.

As shown in FIG. 2, the pinion is carried in the shuttle driving block with the pinion teeth 83 protruding both radially and axially from the shuttle driving block 78. Radially of the shuttle driving block, the pinion teeth 83 mesh with a stationary screw 84, formed internally of the cavity 72 in the shuttle housing block. Axially of the shuttle driving block, the teeth 83 of the pinion extend into a radial slot 85 formed in the flat rear face 41 of the shuttle. Preferably, as shown in FIG. 8, the pinion teeth 83 extend radially only partially into the radial slot 85 and the rear face of the shuttle so that a space is provided in the radial indentations 86 between the pinion teeth 83 for accommodation of needle thread loops as the needle thread loops pass between the shuttle and the pinion during each stitch forming operation.

shuttle. This low velocity rotation of the pinion about its own axis is amply sufficient to pass needle thread {oops between the shuttlte f the shuttle driver and the ow speed of rotation o t e plnron reduces fhe wear and the noise incident to the operation of a machine having this invention applied thereto. With machine speeds of greater than 5,000 stitch forming cycles per minute, successful passage of needle thread loops past the shuttle drive has been obtained with pinion speeds of one-fourth the speed of rotation of the shuttle. it will be appreciated that the speed of rotation of the pinion about its own axis may be varied either by changing the size of the pinion 81 or the pitch of the screw 84.

Having set forth the nature of this invention, what is claimed herein is:

1. In a lockstitch sewing machine having an endwise reciprocatory thread carrying needle and a circularly moving shuttle having means for carrying a supply of locking thread therein, said shuttle being adapted to pass completely through successive loops of needle thread to concatenate said needle and locking threads into lockstitches, a drive mechanism for imparting circular movement to said shuttle comprising, stationary support means on said sewing machine formed with a raceway constraining said shuttle for movement in a circular path, a shuttle driving member supported for circular movement in spaced relation to said stationary support means, a disc rotatably supported on said shuttle driving member on an axis perpendicular to the axis of circular movement of said shuttle member, said shuttle being formed with a radial slot embracing the periphery of said disc, said disc periphery being formed with a radial thread accommodating indentation, and means operatively connected to said disc and effective to impart turning movement to said disc about said disc axis at a rate not greater than one revolution of said disc during each revolution of said shuttle driving member.

2. A shuttle drive mechanism as set forth in claim 1 in which said disc comprises a pinion having evenly spaced teeth defining said radial thread accommodating indentation therebetween.

3. A shuttle drive mechanism as set forth in claim 2 in which said means effective to impart turning movement to said disc comprises a screw carried by said stationary support means and arranged in mesh with said pinion teeth.

4. A shuttle drive mechanism as set forth in claim 3 in which the pitch of said screw is so related to the pitch of the teeth of said pinion that at least one thread accommodating indentation between pinion teeth will be shifted completely through said shuttle slot during each revolution of said shuttle. 

1. In a lockstitch sewing machine having an endwise reciprocatory thread carrying needle and a circularly moving shuttle having means for carrying a supply of locking thread therein, said shuttle being adapted to pass completely through successive loops of needle thread to concatenate said needle and locking threads into lockstitches, a drive mechanism for imparting circular movement to said shuttle comprising, stationary support means on said sewing machine formed with a raceway constraining said shuttle for movement in a circular path, a shuttle driving member supported for circular movement in spaced relation to said stationary support means, a disc rotaTably supported on said shuttle driving member on an axis perpendicular to the axis of circular movement of said shuttle member, said shuttle being formed with a radial slot embracing the periphery of said disc, said disc periphery being formed with a radial thread accommodating indentation, and means operatively connected to said disc and effective to impart turning movement to said disc about said disc axis at a rate not greater than one revolution of said disc during each revolution of said shuttle driving member.
 2. A shuttle drive mechanism as set forth in claim 1 in which said disc comprises a pinion having evenly spaced teeth defining said radial thread accommodating indentation therebetween.
 3. A shuttle drive mechanism as set forth in claim 2 in which said means effective to impart turning movement to said disc comprises a screw carried by said stationary support means and arranged in mesh with said pinion teeth.
 4. A shuttle drive mechanism as set forth in claim 3 in which the pitch of said screw is so related to the pitch of the teeth of said pinion that at least one thread accommodating indentation between pinion teeth will be shifted completely through said shuttle slot during each revolution of said shuttle. 